1. Field of the Invention
The present invention relates to a Liquid Crystal Display (LCD) device, and more particularly, to an apparatus and method for driving an LCD device so as to reduce the number of data driving Integrated Circuits (ICs) and overcome the degradation of image quality caused by the difference between the parasitic capacitances of pixel columns.
2. Discussion of the Related Art
An LCD device displays an image, relying on the electrical and optical characteristics of liquid crystals. The liquid crystals exhibit different anisotropic properties in dielectric constant and refractive index according to long and short molecular axes. The molecular arrangement and optical properties of the liquid crystals are easy to control. The LCD device having these features displays images by controlling the transmittance of light that passes through polarizers through changing the orientation of liquid crystal molecules.
The LCD device includes a liquid crystal panel having a plurality of pixels arranged in a matrix, a gate driver for driving gate lines of the liquid crystal panel, and a data driver for driving data lines of the liquid crystal panel.
Each pixel of the liquid crystal panel represents an intended color by combining Red (R), Green (G) and Blue (B) color subpixels that control light transmittance according to data signals. Each subpixel includes a Thin Film Transistor (TFT) connected to a gate line and a data line and a liquid crystal capacitor connected to the TFT. The liquid crystal capacitor controls the light transmittance by charging the difference voltage between a data signal provided to a pixel electrode and a common voltage supplied to a common electrode and driving a liquid crystal according to the charged voltage.
The gate driver includes a plurality of gate ICs for sequentially driving the gate lines of the liquid crystal panel.
The data driver includes a plurality of data ICs for converting digital data signals to analog data signals and providing the analog data signals to the data lines of the liquid crystal panel, whenever each gate line is driven.
Since a data IC includes complex circuits such as a digital-to-analog converter, etc., its fabrication cost is high. Also, more data ICs than gate ICs are required because the liquid crystal panel has more data lines than gate lines. Accordingly, techniques for reducing the number of data ICs, while maintaining the resolution of a liquid crystal panel at the same level have been proposed.
For instance, a liquid crystal panel with a reduced number of data lines has been proposed, in which every pair of adjacent subpixels share one data line, that is, every pair of adjacent subpixel columns share a single data line interposed between them, to thereby reduce the number of data ICs.
However, when subpixels are disposed at both sides of a data line to reduce the number of data ICs, the difference between the parasitic capacitances of TFTs connected at both sides of each data line causes a flicker phenomenon.
To be more specific, the capacitance of a gate/source electrode differs from that of a gate/drain electrode in the TFTs of pixel columns at both sides of each data line in view of the nature of the fabrication process of the TFTs. The resulting difference in parasitic capacitance between adjacent pixel columns connected to each data line leads to the flicker phenomenon, thus degrading image quality. Moreover, considering the recent trend of displays toward large size, there exists a need for an LCD device that further decreases the number of data ICs and prevents image quality degradation, compared to the conventional LCD device structure with a reduced number of data ICs.